Phase mod with PWM

[Tony Allgood]

>Most typically the PWM feature is built from a sawtooth wave, and the
rising point of....<snip... good description here>

Thank you Don, this is indeed what I should have said.

>But if the PWM feature is built from a triangle wave instead of a
sawtooth wave, both the rising and falling points move in opposite
directions and you won't have that phase modulation effect.

But, I still get a perception of PM from the triangle as well. So I
suppose my question would be 'why am I getting PM from a triangle
wave-pulse output?' However, I may be wrong, perhaps a perfect triangle
is needed to eliminate hearable PM, and I just didn't have one of those.

Don, have you tried this on your modular? Can you veryify that triangle
gets 'better' PWM? I believe Charles Blakey (DigiSound) reckoned that
PWM should be from a triangle source. If this is so, we could get away
with triangle LFOs for smooth PWM.

Regards,

Tony Allgood  Penrith, Cumbria, UK

Rack mounted moog filter and the TB3030 SuperBassline projects:

http://www.techrepairs.freeserve.co.uk/